Bug 14697: Introduce Koha::Checkouts::ReturnClaim(s)

Bug 14697: Introduce Koha::Checkouts::ReturnClaim(s)

This patch introduces the Koha::Object(s)-derived classes for handling
return claims. Tests are added to cover the overloaded ->store method,
and domain-specific exceptions are added as well.

To test:
1. Apply this patches
2. Run:
   $ kshell
  k$ prove t/db_dependent/Koha/Checkouts/ReturnClaim.t
=> SUCCESS: Tests pass!

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: Andrew Fuerste-Henry <andrew@bywatersolutions.com>
Signed-off-by: Lisette Scheer <lisetteslatah@gmail.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>